Fuel injection systems

ABSTRACT

A fuel system for an internal combustion engine includes an accumulator for storing fuel under pressure a plurality of injection valves connected to the accumulator through a conduit a shuttle member for controlling the amount of fuel flowing to the injection valves from the accumulator during an injection stroke and an additional valve operable to permit the return of the shuttle at the other end of the injection stroke.

United States Patent [1 1 Asbery et al.

[451 Feb. 5, 1974 1 1 FUEL INJECTION SYSTEMS [75 Inventors: John Harrison Asbery, Wembley;

Ivor Fenne, Greenford, both of England [73] Assignee: C. A. V. Limited, Birmingham,

England 22 Filed: Oct. 27, 1972 21 Appl. No.: 301,587

[30] Foreign Application Priority Data Oct. 30, 1971 Great Britain 50526/71 [52] [1.5. Cl.. 123/139 AM, 123/139 AS, 123/139 E [51] Int. Cl. F026 5/02 [58] Field of Search 123/139 AM, 139 AS, 139 AT, 123/139 E, 32 AB [56] References Cited UNITED STATES PATENTS 2,863,437 12/1958 Bessiere 123/32 AE 3,036,565 5/1962 Reiners 123/139 AT 3,191,812 6/1965 Asaka et al 123/139 AM 3,516,395 6/1970 Bassot et a1 123/139 AS Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort Flint [5 7] ABSTRACT A fuel system for an internal combustion engine in cludes an accumulator for storing fuel under pressure a plurality of injection valves connected to the accumulator through a conduit a shuttle member for controlling the amount of fuel flowing to the injection valves from the accumulator during an injection stroke and an additional valve operable to permit the return of the shuttle at the other end of the injection stroke.

5 Claims, 1 Drawing Figure FUEL INJECTION SYSTEMS This invention relates to fuel injection systems for supplying fuel to an internal combustion engine and has for its object to provide such a system in a simple and convenient form.

A fuel injection system in accordance with the invention comprises in combination, an accumulator for storing fuel under pressure, a fuel injection nozzle including a valve, the fuel injection nozzle having an inlet communicating with the accumulator by way of a conduit, first means for opening said valve to allow fuel to flow through an outlet of the nozzle, a further valve disposed in said conduit upstream of said valve, further means for opening said further valve, a cylinder the opposite ends of which communicate with said conduit on the opposite sides respectively of said furthervalve, a shuttle movable in said cylinder, resilient means loading said shuttle towards the end of the cylinder which communicates with the upstream side of the further valve and means for operating said valves in timed relationship with each other and with the engine with which the system is associated, the arrangement being such that with the first mentioned valve closed at the end of injection of fuel, the further valve is opened to allow the .shuttle to move under the action of its resilient loading whereafter the further valve is closed and the first mentioned valve is opened when injection of fuel is required, the shuttle when the first mentioned valve is opened moving against the action ofits resilient loading.

One example of a liquid fuel injection system in accordance with the invention will now be described with reference to the accompanying drawing which shows the system in diagramatic form.

With reference to the drawing thereis provided an accumulator in which is stored liquid fuel at a high pressure. The accumulator is provided with an inlet which communicates with the outlet ofa fuel pump 11.

The accumulator is provided withan outlet which communicates with a conduit 12 and this conduit communicates with an injection nozzle, three such nozzles being shown at 13. Each injection nozzle includes a valve member 14 which can be moved to the open position to permit fuel-from the conduit toflow through an outlet 14a into a combustion space of the associated engine. The valve members 14 are provided with armatures 15 which are associated with solenoids 16 respectively. Furthermore, each valve member has an extension which terminates in a piston 17 slidable within a cylinder the closed end of which communicates with the accumulator by way of a conduit 18. The size of the piston 17 is such that with accumulator pressure existing in both conduits 12 and 1 8, the valve members 14 will be held in the closed position but they can be opened to permit fuel to flow through the outlets 14a by energising the respective solenoids 16.

Also provided is a further valve 19 and this is disposed in the conduit 12 upstream of the valves 13. The valve 19 is of similar construction to the valves 13.

In order to control the quantity of fuel which is supplied by the accumulator there is provided a cylinder 20 the opposite ends of which communicate with the conduit 12 on opposite sides of the valve 19 respectively. Mounted within the cylinder is a slidable shuttle 21 and this is loaded by means of a coiled compression spring 22, towards the end of the cylinder connected with the upstream side of the conduit 12.

In operation, at the end of an injection period all the valves 13 wil be closed and the shuttle 21 will be in contact with a step 21a defined in the wall of the cylinder 20. The valve 19 is then opened and the shuttle moves towards the other end of the cylinder under the action of the spring, the shuttle itself being pressure balanced since the opening of the valve 19 places the end of the cylinder containing the spring in communication with the accumulator. The valve 19 is then closed and the appropriate valve 13 is then opened when fuel is required to be injected to the engine. As soon as a valve 13 is opened the shuttle moves against the action of the spring 22 and fuel is displaced from the end of the cylinder containing the spring, to the associated engine. Following the end of injection which occurs when the shuttle contacts the step, the valve 13 closes and the cycle is repeated.

In order to lower the pressure in the conduit 12 at the end of injection so that a rapid closure of the valve 13 is obtained, the shuttle 21 is provided with a port 23 in its wall and this port communicates by way of an internal passage in the shuttle, with the end of the cylinder containing the spring. Moreover, formed in the wall of the cylinder is a port 24 which communicates with one end of a cylinder containing a spring loaded piston 25. The other end of the cylinder containing the piston 25 is maintained at a fairly low pressure. The arrangement is such that during movement of the shuttle 21 against the action of its spring the ports 23 and 24 will be brought into register and when this occurs injection of fuel through the particular nozzle is terminated and the fuel displaced by the remaining stroke of the shuttle flows through the port 24 and effects movement of the piston 25 against the action of its spring. The quantity of fuel delivered at part load is determined by the amount of time valve 19 is open to allow the shuttle 21 to move back towards its stop under the action of the spring. The maximum fuel which can be supplied is determined by the stroke of the shuttle against the action of the spring and until the ports 24 and 25 are brought into register.

Piston 25 is returned under the action'of its resilient loading thereby displacing the fuel volume it absorbed at the end of the previous injection period, to drain. This movement occurs when movement of the shuttle 21 connects port 24 to drain.

In order to control the energisation of the solenoids 16 which control the valves 13 and the solenoid which controls the valve 19 an electric switch unit 27 is provided whereby the valves operate in the correct sequence and in timed relationship with the associated engine. The switch unit 27 may be driven directly by the engine or recieve signals from the engine indicative of speed and engine position so that injection of fuel to the engine is achieved at the correct time.

We claim:

1. A fuel injection system for supplying fuel to an internal combustion engine and comprising in combination, an accumulator for storing fuel under pressure, a fuel injection nozzle including a valve, the fuel injection nozzle having an inlet communicating with the accumulator by way of a conduit, first means for opening said valve to allow fuel to flow through an outlet of the nozzle, a further valve disposed in said conduit upstream of said valve, further means for opening said further valve, a cylinder the opposite ends of which communicate with said conduit on the opposite sides respectively of said further valve, a shuttle movable in said cylinder, resilient means loading said shuttle towards the end of the cylinder which communicates with the upstream side of the further valve and means for operating said valve in timed relationship with each other and with the engine with which the system is associated, the arrangement being such that with the first mentioned valve closed at the end of injection of fuel, the further valve is opened to allow the shuttle to move under the action of its resilient loading whereafter the further valve is closed and the first mentioned valve is opened when injection of fuel is required, the shuttle when the first mentioned vlave is opened moving against the action of its resilient loading and fuel is displaced from the end of the cylinder containing the spring.

2. A system as claimed in claim 1 including cooperating port means in the shuttle and cylinder whereby at a predetermined position in the movement of the shuttle against the action of its resilient loading the port means will be brought into communication so that the pressure of fuel downstream of the cylinder will be reduced to a lower value thereby to terminate injection of fuel to the engine.

3. A system as claimed in claim 2 in which the port means in the cylinder comprises a port in the wall thereof said port communicating with one end ofa cylinder containing a resiliently loaded piston.

4. A system as claimed in claim 3 in which the valve members of said valve and said further valves are associated with pistons respectively which are subjected to the pressure of fuel within the accumulator whereby the valve members are pressure actuated towards the closed position.

5. A system as claimed in claim 4 including solenoids respectively for effecting movement of the valve members towards the open position. 

1. A fuel injection system for supplying fuel to an internal combustion engine and comprising in combination, an accumulator for storing fuel under pressure, a fuel injection nozzle including a valve, the fuel injection nozzle having an inlet communicating with the accumulator by way of a conduit, first means for opening said valve to allow fuel to flow through an outlet of the nozzle, a further valve disposed in said conduit upstream of said valve, further means for opening said further valve, a cylinder the opposite ends of which communicate with said conduit on the opposite sides respectively of said further valve, a shutTle movable in said cylinder, resilient means loading said shuttle towards the end of the cylinder which communicates with the upstream side of the further valve and means for operating said valve in timed relationship with each other and with the engine with which the system is associated, the arrangement being such that with the first mentioned valve closed at the end of injection of fuel, the further valve is opened to allow the shuttle to move under the action of its resilient loading whereafter the further valve is closed and the first mentioned valve is opened when injection of fuel is required, the shuttle when the first mentioned vlave is opened moving against the action of its resilient loading and fuel is displaced from the end of the cylinder containing the spring.
 2. A system as claimed in claim 1 including co-operating port means in the shuttle and cylinder whereby at a predetermined position in the movement of the shuttle against the action of its resilient loading the port means will be brought into communication so that the pressure of fuel downstream of the cylinder will be reduced to a lower value thereby to terminate injection of fuel to the engine.
 3. A system as claimed in claim 2 in which the port means in the cylinder comprises a port in the wall thereof said port communicating with one end of a cylinder containing a resiliently loaded piston.
 4. A system as claimed in claim 3 in which the valve members of said valve and said further valves are associated with pistons respectively which are subjected to the pressure of fuel within the accumulator whereby the valve members are pressure actuated towards the closed position.
 5. A system as claimed in claim 4 including solenoids respectively for effecting movement of the valve members towards the open position. 